This invention relates to electrical connectors having a means for providing an electrical grounding connection. More particularly, though not exclusively, this invention relates to shielded electrical connectors.
Electrical connectors having a means for providing an electrical grounding connection are well known. These connectors are often used for mechanically and electrically coupling shielded cables, which are electrical cables in which one or more insulated inner conductor is enclosed by a conductive shielding layer. Where there is a single insulated inner conductor, shielded cables are sometimes called coaxial cables.
Shielded cables are used in applications where it is desired to minimized the effect of electrical noise on signals which are being carried in the cables or to reduce the electromagnetic radiation emitted by the cables. The former is particularly important for cables carrying high bandwidth signals which are particularly susceptible to noise. The latter is important for cables carrying high voltages.
In a shielded cable, the shielding is usually in the form of plated braided strands of copper which surround the inner conductor(s), although other conductive shielding arrangements such as spiral windings of metallic foil and sleeves of conductive polymers are also known. The shielding is usually grounded, although the shielding may in some applications carry signals. In either case, it is important that the electrical connector maintains the shielding and provide a reliable electrical connection for both the inner conductor(s) and the shielding/grounding.
In a known shielded electrical connector, the shielding/grounding connection is provided by a rigid conductive sleeve arranged around a dielectric spacing member, which spacing member accommodates at least one elongate contact terminal for connecting the inner conductors. The metallic sleeve functions to provide the mechanical coupling of the connector, and the electrical coupling of the shielding/grounding, to a cable at one end and a mating connector at the other end.
In the known shielded electrical connector, the mechanical coupling means often includes circumferential “keys” which have to be aligned with circumferential recesses or cut outs provided in the conductive sleeve of a mating connector. The electrical coupling means usually comprises a resilient metallic band arranged around the conductive sleeve of the connector. The resilient band has an interference fit with the sleeve of the mating connector, so as to ensure reliable electrical contact. That is to say, the resilient band holds itself in position by being diametrically smaller than the sleeve so that the band exerts a positive compressive spring force.
A problem associated with the known connector described above is that the resilient metallic band used for electrically connecting the shielding consumes space in the axial direction of the connector. For example, in a typical known connector, the width of the resilient metallic band can be as much as 6 mm.